( function () {
class DDSLoader extends THREE.CompressedTextureLoader {
  constructor(manager) {
    super(manager);
  }

  parse(buffer, loadMipmaps) {
    const dds = {
      mipmaps: [],
      width: 0,
      height: 0,
      format: null,
      mipmapCount: 1
    }; // Adapted from @toji's DDS utils
    // https://github.com/toji/webgl-texture-utils/blob/master/texture-util/dds.js
    // All values and structures referenced from:
    // http://msdn.microsoft.com/en-us/library/bb943991.aspx/

    const DDS_MAGIC = 0x20534444; // let DDSD_CAPS = 0x1;
    // let DDSD_HEIGHT = 0x2;
    // let DDSD_WIDTH = 0x4;
    // let DDSD_PITCH = 0x8;
    // let DDSD_PIXELFORMAT = 0x1000;

    const DDSD_MIPMAPCOUNT = 0x20000; // let DDSD_LINEARSIZE = 0x80000;
    // let DDSD_DEPTH = 0x800000;
    // let DDSCAPS_COMPLEX = 0x8;
    // let DDSCAPS_MIPMAP = 0x400000;
    // let DDSCAPS_TEXTURE = 0x1000;

    const DDSCAPS2_CUBEMAP = 0x200;
    const DDSCAPS2_CUBEMAP_POSITIVEX = 0x400;
    const DDSCAPS2_CUBEMAP_NEGATIVEX = 0x800;
    const DDSCAPS2_CUBEMAP_POSITIVEY = 0x1000;
    const DDSCAPS2_CUBEMAP_NEGATIVEY = 0x2000;
    const DDSCAPS2_CUBEMAP_POSITIVEZ = 0x4000;
    const DDSCAPS2_CUBEMAP_NEGATIVEZ = 0x8000; // let DDSCAPS2_VOLUME = 0x200000;
    // let DDPF_ALPHAPIXELS = 0x1;
    // let DDPF_ALPHA = 0x2;

    const DDPF_FOURCC = 0x4; // let DDPF_RGB = 0x40;
    // let DDPF_YUV = 0x200;
    // let DDPF_LUMINANCE = 0x20000;

    function fourCCToInt32(value) {
      return value.charCodeAt(0) + (value.charCodeAt(1) << 8) + (value.charCodeAt(2) << 16) + (value.charCodeAt(3) << 24);
    }

    function int32ToFourCC(value) {
      return String.fromCharCode(value & 0xff, value >> 8 & 0xff, value >> 16 & 0xff, value >> 24 & 0xff);
    }

    function loadARGBMip(buffer, dataOffset, width, height) {
      const dataLength = width * height * 4;
      const srcBuffer = new Uint8Array(buffer, dataOffset, dataLength);
      const byteArray = new Uint8Array(dataLength);
      let dst = 0;
      let src = 0;

      for (let y = 0; y < height; y++) {
        for (let x = 0; x < width; x++) {
          const b = srcBuffer[src];
          src++;
          const g = srcBuffer[src];
          src++;
          const r = srcBuffer[src];
          src++;
          const a = srcBuffer[src];
          src++;
          byteArray[dst] = r;
          dst++; //r

          byteArray[dst] = g;
          dst++; //g

          byteArray[dst] = b;
          dst++; //b

          byteArray[dst] = a;
          dst++; //a
        }
      }

      return byteArray;
    }

    const FOURCC_DXT1 = fourCCToInt32('DXT1');
    const FOURCC_DXT3 = fourCCToInt32('DXT3');
    const FOURCC_DXT5 = fourCCToInt32('DXT5');
    const FOURCC_ETC1 = fourCCToInt32('ETC1');
    const headerLengthInt = 31; // The header length in 32 bit ints
    // Offsets into the header array

    const off_magic = 0;
    const off_size = 1;
    const off_flags = 2;
    const off_height = 3;
    const off_width = 4;
    const off_mipmapCount = 7;
    const off_pfFlags = 20;
    const off_pfFourCC = 21;
    const off_RGBBitCount = 22;
    const off_RBitMask = 23;
    const off_GBitMask = 24;
    const off_BBitMask = 25;
    const off_ABitMask = 26; // let off_caps = 27;

    const off_caps2 = 28; // let off_caps3 = 29;
    // let off_caps4 = 30;
    // Parse header

    const header = new Int32Array(buffer, 0, headerLengthInt);

    if (header[off_magic] !== DDS_MAGIC) {
      console.error('THREE.DDSLoader.parse: Invalid magic number in DDS header.');
      return dds;
    }

    if (!header[off_pfFlags] & DDPF_FOURCC) {
      console.error('THREE.DDSLoader.parse: Unsupported format, must contain a FourCC code.');
      return dds;
    }

    let blockBytes;
    const fourCC = header[off_pfFourCC];
    let isRGBAUncompressed = false;

    switch (fourCC) {
      case FOURCC_DXT1:
        blockBytes = 8;
        dds.format = THREE.RGB_S3TC_DXT1_Format;
        break;

      case FOURCC_DXT3:
        blockBytes = 16;
        dds.format = THREE.RGBA_S3TC_DXT3_Format;
        break;

      case FOURCC_DXT5:
        blockBytes = 16;
        dds.format = THREE.RGBA_S3TC_DXT5_Format;
        break;

      case FOURCC_ETC1:
        blockBytes = 8;
        dds.format = THREE.RGB_ETC1_Format;
        break;

      default:
        if (header[off_RGBBitCount] === 32 && header[off_RBitMask] & 0xff0000 && header[off_GBitMask] & 0xff00 && header[off_BBitMask] & 0xff && header[off_ABitMask] & 0xff000000) {
          isRGBAUncompressed = true;
          blockBytes = 64;
          dds.format = THREE.RGBAFormat;
        } else {
          console.error('THREE.DDSLoader.parse: Unsupported FourCC code ', int32ToFourCC(fourCC));
          return dds;
        }

    }

    dds.mipmapCount = 1;

    if (header[off_flags] & DDSD_MIPMAPCOUNT && loadMipmaps !== false) {
      dds.mipmapCount = Math.max(1, header[off_mipmapCount]);
    }

    const caps2 = header[off_caps2];
    dds.isCubemap = caps2 & DDSCAPS2_CUBEMAP ? true : false;

    if (dds.isCubemap && (!(caps2 & DDSCAPS2_CUBEMAP_POSITIVEX) || !(caps2 & DDSCAPS2_CUBEMAP_NEGATIVEX) || !(caps2 & DDSCAPS2_CUBEMAP_POSITIVEY) || !(caps2 & DDSCAPS2_CUBEMAP_NEGATIVEY) || !(caps2 & DDSCAPS2_CUBEMAP_POSITIVEZ) || !(caps2 & DDSCAPS2_CUBEMAP_NEGATIVEZ))) {
      console.error('THREE.DDSLoader.parse: Incomplete cubemap faces');
      return dds;
    }

    dds.width = header[off_width];
    dds.height = header[off_height];
    let dataOffset = header[off_size] + 4; // Extract mipmaps buffers

    const faces = dds.isCubemap ? 6 : 1;

    for (let face = 0; face < faces; face++) {
      let width = dds.width;
      let height = dds.height;

      for (let i = 0; i < dds.mipmapCount; i++) {
        let byteArray, dataLength;

        if (isRGBAUncompressed) {
          byteArray = loadARGBMip(buffer, dataOffset, width, height);
          dataLength = byteArray.length;
        } else {
          dataLength = Math.max(4, width) / 4 * Math.max(4, height) / 4 * blockBytes;
          byteArray = new Uint8Array(buffer, dataOffset, dataLength);
        }

        const mipmap = {
          'data': byteArray,
          'width': width,
          'height': height
        };
        dds.mipmaps.push(mipmap);
        dataOffset += dataLength;
        width = Math.max(width >> 1, 1);
        height = Math.max(height >> 1, 1);
      }
    }

    return dds;
  }

}

THREE.DDSLoader = DDSLoader;
} )();
